Among such devices, the most advanced to date include a matrix tightener comprising a turning pin attached to a casing within which the pin itself pulls the matrix in its rotation, placing it into tension, and a tightening device that can be attached to the above-mentioned pin when the matrix tightener is already applied with the relative matrix around the tooth, so as to be capable of making it rotate while tightening the matrix and making it adhere to the outer walls of the tooth itself.
An example of device made in this way is provided by U.S. Pat. No. 4,396,374, for example.
The drawback that is encountered in the use of device of this type is that of the insufficient ease of handling: in fact it is necessary to first apply the matrix tightener and the matrix, with the matrix not yet in tension, while manually maintaining in position in the oral cavity, and then to insert the tightening device by attaching it the matrix tightener, while still manually holding the matrix, until it has been placed in tension. All this involves significant practical difficulties and a situation of prolonged discomfort for the patient.
The inventor of the present invention has attempted to eliminate this drawback by working out a unit including both a matrix tightener and a turnbuckle which can be made integral, so that the matrix can be applied, maintained in the correct position and tightened merely by inserting and subsequently activating the tightening device, which moves with itself the matrix which is integral with it.